Not the reply you are looking for but can I suggest something equally as cheap! Juggling.........while it may sound totally strange....it actually works to improve hand/eye coordination. Really improves your scan. Did a recent aptitude test/Sim check and passed both followed by a job offer; I think juggling helped in some way. Also a good way to relax and it is good fun.
Sorry I don't have any suggestions for Internet sites to assist but hope this other unconventional suggestion helps you out!
brgds,
GP.